Why Can’t Humans Differentiate Between Animals Of The Same Species?

Can you spot any difference between the two pandas?

If you weren’t able to, don’t worry! You’re one of the many unsuccessful people who continue to be failed by their adult brains. You’ll also be surprised to know who would be much better at spotting the difference… Babies younger than 6 months old!


Inadequacies of the Adult Brain

Research shows that 6-month-old infants are able to differentiate and recognize individual faces of monkeys. However, as they grow older, this same ability disappears by 9 months of age.  Only those babies who were presented with pictures of monkeys during the intervening time (between 6 – 9 months) were successful at differentiating between the faces of monkeys even at 9 months. Changes happening as a result of brain maturation are believed to be the culprit behind the loss of this ability.


Does this mean we become less perceptive as we age?

No! It has been shown that babies develop a racial bias, i.e., a preference for faces belonging to their own race, as well as a greater ability to understand those faces’ emotional expressions than faces or facial expressions of other races, by the time they reach 9 months of age. In other words, you win some, you lose some… infants aren’t perfect either.

Why do we only lose the discriminating ability for animals?

As babies grow older, they mostly interact with human faces and therefore get better at recognizing and discriminating human faces.  In scientific circles, this process is called perceptual narrowing. Perceptual narrowing for human faces also has a survival advantage that has evolutionary foundations. Preference for faces of the same race follows the same logic.


What Changes in the Brain?

We are born with almost perfect hardware in our neural network, which is rich in connections. As babies grow, the connections that are used (identifying and discriminating human faces) are strengthened, while the ones not in use break away or are redirected (connections for discriminating animal faces).  This process is called neuronal pruning. Therefore, just like our ancestral tails disappeared because they were not in use anymore when apes began living on the ground, instead of in trees, the brain similarly loses its ability to distinguish between the finer features of faces from other species as we grow up. If we don’t use the wiring anymore, our brain tries to be more efficient and dedicates our cognitive energy elsewhere.


However, like the babies in the research study, if infants are exposed to animal faces throughout their development, the connections will be in frequent use, so the ability will be retained. Hence, pet owners have been found to be slightly better at discriminating between animal faces. That being said, in general, our developing brain follows the rule – keep what you use and switch off what you don’t!

In contrast, animals retain their ability to tell human individuals apart. It seems like the four-legged kingdom is the winner of this ‘Face’-off!


  1. Perceptual Narrowing – Wikipedia
  2. Synaptic Pruning – Wikipedia
  3. Synaptic Pruning Mechanisms in Learning – Princeton CS (Princeton University)
The short URL of the present article is: http://sciabc.us/XNNVC
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About the Author

Rujuta has a MA in Counseling Psychology and MSc in Cognitive Science. She is currently pursuing a PhD in Cognitive Science from IIT Kanpur in India. Her primary area of interest being human memory and learning, she is also interested in the neuroscience of cognitive processes. She also identifies herself as a bibliophile and a harry potter fanatic.

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